Good question, my friend!..
Personally, the only previous L / future E (New Aircraft Categorization for 3.0) aircraft that I have unlocked is the B789. It’s a bit pricey, nowadays, but was a good compromise between range and profitability in version 1.x (when I unlocked it).
Regarding the A35K, it’s got one the longer in-game ranges of all models, only behind the B77L, if I’m not mistaken. However, the A35K will earn you more XP (at level 10, 135 for the A35K vs. 109 for the B77L). In terms of SP, if you compare the same route, the A35K should be higher, considering it has more seating capacity.
Comparing the Boeing Triple 7 and the 747-400, the unlocking cost of the B77W is double the cost for the B744 (56 vs. 28).
In terms of XP (level 10), 119 for the B77W vs. 135 for the B744.
The seating capacity is the same (one of the design objectives of the initial triple 7 project was exactly a twin engine aircraft to replace the 747).
The range of the B744 is better, but not by much.
The 747 takes a little longer to be handled and requires 3 more handling agents. Something to consider.
I agree with @Thatflyerguy regarding the Wollars profitability, when it comes to the B744 and the Dreamliners (the B789, in particular).
But, getting back to your question, I’d probably go with the A343 (I’m actually planning on unlocking the A346). Much better range, which gives you more flexibility. And better seating capacity, too. At 22 GP, I think it’s preferable to the A332. But be mindful of the Wollar cost, which is 74k higher for the A343 compared to the A332.
Have you thought about a cargo airplane? They don’t have the range of the pax ones, but in terms of XP, there’s a considerable difference.
And LHR it’s not too bad, in terms of cargo stands.
I hope you find this information useful.