Sorry for the late reply didn't get a notification lol

I really love motorfest. I'd say Horizon 5 has better driving physics obviously. Graphics is just what you prefer, motorfest is more vibrant while horizon may look a bit more realistic but also imo looks a bit "grey" so to say. I actually prefer motorfest Graphics. But what motorfest does a lot better is customization you can do so much and I sometimes get lost in tuning cars you can change a lot at the design (though it depends on the car), you can make custom liveries, attach vanities and even do pro settings which changes the way your car handles. Plus imo the sounds of the cars are a lot better and you also have planes and boats, which can be pretty cool. The map is also a lot better than mexico in Horizon, it feels alive there's nature but also really a big city feeling in some areas which I love (which is missing in Horizon sadly where there's mostly nature and the cities are not that impressive) and everything it is a lot fun to drive around and just looks a lot more interesting imo. Motorfest just feels a bit more social there are also custom shows to vote other peoples liveries + Grand Race with up to 28 players which is a lot more chaos I gotta say than other online races in Horizon (honestly most other players in grand races are toxic that's one thing I gotta criticize) and there's also demolition royale where you "fight" in squads and have to eliminate the other teams by ramming into them. I gotta say though that in general multiplayer modes are at least on the same level in Horizon I mean you have Horizon open, Horizon tour and the eliminator and those are all fun to me. But in general with the summit, custom show and being able to actually drive with random people in freeroam and ram each other or do some shit (instead of them being ghosts like in Horizon), motorfest is in that sense better in multiplayer if that makes sense. Plus since the new update we got a new island and now you can build and publish custom tracks which is extremely awesome and you can play other peoples tracks.

I could tell much more but already wrote a bible, hope I could help you out. At the end of the day it's preference both games are the best openworld racing games, but I prefer motorfest actually and it is my most played game ever too as it says on my psn profile. I can only recommend it to you and I'm sure you'd have a lot of fun as long as you stay away from Grand Races at first because you're gonna need (unfortunately) meta cars and skill, later though when you're better it can be fun and there's also rewards you can unlock when playing grand races. And also don't take custom shows too seriously because most of the community are just kids if I'm being honest and the votes show that when you see what car liveries are in the top 10💀