Vanguard. Anyone that says otherwise hasn't played both properly.
Oh and if you can get EBB Vanguard OMG go for it.
L1 has fantastic hitting power, typical of UK, but with pretty crappy range in-battle, also very typical of UK.
You can front gun it but again, if you haven't played UK properly, you really are noobing out for something that UK isn't designed for. It does speed well in the ships it is supposed to (POW or maybe Nelson if you decide to go for speed)
UK hits well. Play for that advantage. You don't play to be the fastest, but speed is an added extra at time. You play to devastate.
Vanguard gives you the in-battle range equivalent to a H39, which allows you to take on most things, with extremely good accuracy with high gunners, which along with 30 degree guns is unstoppable (ask anyone that owns QV)
Lion 1 gives you around half an inch (zoomed out) less range, which can be important but hits like you wouldn't believe.
Once you get to BB4, you don't play for speed, and shouldn't play to take a hit either.
Vanny will manage around 40 knots I believe, and L1 maybe 44 knots. This is unarmoured. Couldn't even bring myself to tell you what the numbers are for armoured.
You dodge in range and smash like Hulk, or you stay at arms length and hit like Naseem.
Faster reload, lower angle (more crits = more damage) and more shells
BTW I took Revenge up to L1 (gunners roughly 8-10 levels above BO as should be) then switched to Renown which quickly turned to Repulse and then all the way through Vanguard. This was 2 BOs of course, which is customary of me.
Of course it's up to you, but if you have sense you would choose Vanguard and have more fun in L1 once your engis are higher level so you can go fast for a while, and your gunners are even higher to allow you to smash people.
And play gradual on L1 if you can. You'll be pleasantly surprised :)