Roosevelt, Grimm, Russo, the Jacksons. History is full of great families, and the 7 Series is also on this list, with seven generations of the luxury flagship offering customers the world over cosseting luxury and unrivalled power.

However, where previous iterations of the luxury limousine traced a clear lineage from generation to generation, the family line is now diverging, being made available for the first time with either electric or combustion power.

This means that customers now have the option to choose between two brothers: The first, offering new-age electric power, while the second, the purr of the creamy six-cylinder.

But just which of the two BMW luxury limousines should you make yours? We send two of our Writer 'brothers' to find out!

The new BMW i7 takes the quiet and effortlessness you'd expect from a luxury limousine to a new level

Being the newest entrant to inherit a prestigious family name comes with a lot of expectations. It's not easy to stand out when your elder brother has had a significant head start in life. But starting out later also means you've had the opportunity to learn from the very best. That's exactly why I've opted for this new BMW i7.

You see, I've learnt so much when it comes to publishing and writing from my elder 'brother' Jeremy, and this BMW i7 is very much the same: Customers shop for a luxury limousine because they are seeking the best in cabin comfort, and this new i7 has, in the same fashion, inherited all the lessons of 7 Series' of old, to offer newfound levels of quiet refinement.

The CLAR architecture on which it sits, is the product of generations of development since the first E23 7 Series, and now offers the best in cabin isolation from all that is happening around you. So, when I'm driven around, I know I'm getting the best there is in comfort.

And this perfected ride quality also means I get to fully appreciate all the features that come in this i7, such as the luxuriant seats upholstered in Merino leather, or the handy 5.5-inch touch control displays at either door which allow me to easily set the climate exactly as I want it.

Put on some Lo-fi music through its 21-speaker Bowers and Wilkins surround sound system, and the cabin of the BMW i7 quickly becomes the perfect place to simply lounge in and unwind after a long day at work.

And when I do take the helm myself, I always travel knowing I have one of the best drivetrains there is. The fifth generation eDrive technology from BMW - that's also found in cars including the iX3 and iX - is now applied here to offer a total of 536bhp and 745Nm of torque making every drive as it should be: Completely effortless.

But the drive is not all that matters here, of course. Beyond motoring with zero local emissions, there's also the fact that this eDrive technology has eliminated the need for rare-earth materials in its rotors.

Plus, the suppliers of the lithium and cobalt used to make the batteries are held to stringent standards when it comes to sourcing, and production in Plant Dingolfing is powered by renewable energy.

So, this i7 is a mighty sustainable machine, even before the first turn of its wheels.

And when it comes to charging, you won't have to sweat with the i7 either. Customers in Singapore can opt to get their car with a 10,000kWh three-year public charging subscription package with Shell, facilitating easy fast charging at any Shell Recharge station.

Alternatively, the car can come with a complimentary installation service for a wall-mounted AC charger for your home, which will charge the i7's 101.7kWh battery at 11kW.

What all this means, of course, is that the BMW i7 delivers effortless mobility while being sustainable. And that's what makes it so great: It powers today's needs without compromising on the opportunities available for future generations to come. And that's exactly the sort of thinking that will keep a family line going strong.

The BMW 7 Series exudes class and sophistication, perfect for those that want to appreciate the finer things in life

The 735i is ideal for folks like me who don't always feel the need to be 'charging about'. After all, we are in a 7 Series; surely the whole point of a limousine is to arrive unruffled and in style.

And this 735i is specifically designed to cater to this. Approach it and the head lights don't just illuminate - they actually sparkle because of the Swarovski crystals integrated into the daytime running lights. This also gives the light a shimmering quality that cannot be replicated. Aesthetics aside, the light show isn't just for well, show. The crystal lights function as side lights, too.

Further distinguishing the 7 Series in this segment are the semi-automatic opening/closing doors. Luxury means effortlessness, and what could be easier than having doors that open and close on command? Indeed, my guests will be even more impressed when all the doors magically open as they approach the car - a function easily activated with the key fob.

The interior is even more impressive than the exterior, for it's a space where advanced technology meets swanky design. My eyes are immediately drawn to the Curved Display, which houses the 12.3-inch information display for the driver and the even larger 14.3-inch control display for the infotainment.

Powered by BMW Operating System 8, both systems are intuitive, customisable, and have gorgeous graphics. The navigation system is nifty as well, using augmented reality 'arrows' overlaid on live camera footage to conveniently and accurately inform the driver where he needs to turn. Perfect for confusing junctions and slip roads.

Sitting below the Curved Display is the aptly named Interaction Bar. Just like the car's shimmering head lights, the Interaction Bar is more than a decorative element. Apart from being an ambient light source, its touch-sensitive panels let the driver adjust the climate settings and open the glove compartment as well.

After a long day at the office, though, I admit that it's the 7 Series' backseat that appeals to me. The seats feel pillowy-soft at first, but there's a firmness beneath the initial layer providing excellent support. And though I may enjoy lounging in the back, it doesn't mean I'm no longer in command.

Using the touchscreens on the door panels, I can adjust the air temperature, scroll through my tunes, open/close the blinds, and tweak the ambient lighting. Everything in here that can make my journey more comfortable is at my fingertips.

I love cars and driving, though, so in my heart, I belong in the driver's seat. And while Clarence prefers the quiet isolation of the BMW i7, I daresay the purr of the creamy six-cylinder beneath the 735i's bonnet is even more compelling.

Smoothness, sound, and performance are mainly why BMW's six-cylinder powerplants are so renowned. This turbocharged 3.0-litre engine is no exception, producing 268bhp and 400Nm of torque and propelling the 735i from a standstill to 100km/h in 6.7 seconds.

Acceleration aside, it's the sheer refinement of the straight-six that wows. Quiet and unobtrusive at idle and low speeds, it emits a throaty soundtrack when pushed. It's a reminder that despite being a flagship limo, the 735i retains the sporty character and the BMW-ness that endears the brand to millions.

The 735i is the car for taking it all in and appreciating your success. After all, one must take the time to look back in order to see how far they'be come.

A new generation, the same great family

So, is the 7 Series better as an electric or combustion engine model? It's a question that only the driver can answer. But if you ask us, we'd say it's best to see the i7 and 735i as siblings that complement, rather than compete against one another.

Both cars are superbly engineered, deliver sheer driving pleasure and with so much on-board technology, are designed to please the owner even if he or she is in the backseat.

If the 735i remains the benchmark for modern limousines and the i7 shows us the way forward, how can you go wrong with either choice?