Well having only just started to get the hang of it I was kind of hoping to stick with the FR35...
However the mod I really had in mind which I think is truly fantastic, I was not going to suggest as it's a historic and I did not know if you guys were interested in historics, but now it's mentioned several times already, the Matra F1.
The beauty of the Matra, is it's an extension to the ISI Eve F1, so it has all the top quality ISI physics + the 3rd party addition of the V12 engine and V12 sounds, and the sounds are REALLY awesome! Best sounding mod I have ever heard. A league with this mod will be truly spectacular! I think the standard Eve F1 is already one of the best mods in the game, the Matra is really the icing on the cake.
There is the ISI Brabham BT20, also perfectly fine, but I find rather boring in comparison to the F1 EVE (ISI's generic 60's F1/F2/F3 open wheelers), remember the Matra is based on the EVE F1, I would take the Eve/Matra over the BT20 everyday of the week although there is no problem with the mod, its just way less fun.
I have also driven the ASR F1'92 mod, its it also really excellent. A lot of the 3rd party modern F1 mods seem to feature this kind of codemasters superglue style physics where you can fly into a corner at 160mph, keep the gas planted, take so much kerb so hard you should really have broke the suspension, yet the car just zooms around the corner somehow. It can be good fun but not at all realistic.
The F1 '92 mod is not like this thankfully, yet it is still very drivable. And of course it features the Andrea Moda! I heard of the legal issues, but since then people are still hosting races with the mod, including race dept who keep things above board, so I do not think you will have lawyers knocking on Brets door. In the race dept 30 min race last week a lot of engines broke after 25 mins+, perhaps due to driver error, perhaps not, need to test. This mod has enjoyed a wave of popularity and many people have it installed, I am surprised the same has not happened with the Matra.
The only other modern F1 mod I think worthy of consideration is the ISI Marussia.
I tried this new 2014 F1 mod, it was very good visually and the physics were kind of OK, but it just so nuts I think it would be very hard to have a successful race or league with it. I drove it at modern Monza, coming into t1 at top whack, the cars have 8 gears and the stop on a sixpence so u gotta down shift all them gears in 1 second and if you do not get it right then the engine is blown up, its VERY easy to do. Everybody was blowing engines all the time, including me, often within 1 lap! Aside from this, I just think the performance is so extreme the races will be a shambles unless you have a whole grid full of well practiced Bogdans.
There is also the Mak F2 which is also very nice.
So I concur with the suggestions made so far, Matra, Eve historics, ASR F1 92, ISI Marussia as an outsider, we could add the Mak Corp F2 to the list perhaps.
For me, the 2 stand out candidates are the Matra F1 and the ASR F1 '92 mods.
The great thing about this discussion is all the mods suggested this far are all great mods, I always live in fear at this point of the season that the next mod chosen may not be a good one, but there seems little chance of that here which is very reassuring
Did seem to me about 15x slower water clearing, its the first wet race I have done in b798, in previous builds as you mention it happened much faster.
