I have been playing Forza since Motorsport 2, unfortunately i stopped at Horizon, since the newer games are on the Xbox One, and no i don’t have nor do i want to try Horizon 2 360 edition, so over the years i saw the music of each game change dramatically one after the other, the first FM games where just licensed music up until FM3 where there was this mix in half licensed music half instrumental music, in FM4 the music started to go more even more instrumental, now on Forza 5 i was just blown away by the orchestral music put into the game, and i have a passion to this kind of music, but i got slightly disappointed with Forza 6, it still has good orchestral music, but it’s missing something, I would say that Forza 5, to me, add the best music I’ve heard for quite some time, now on another note, the Horizon series, yeah, i don’t think we need to go to those, it basically has a bunch of music for every taste, but you can pick it as well.
And on that wrap up, my question remains, what do you guys thinking was your favorite “OST” in the Forza series?
Forza 1. Watched someone play it last year and the music was great. FM5 and FM6 had boring music for the most part. It never made me excited to play.
NFS underground and GTA Vice City had my favorites. The tunes matched the cars. Horizon tries but it fails. The game play + lighting + car choices don’t mesh well with cars that are in the game. I know the excitement that occurs driving to a rave or dance party. Horizon makes me feel like I’m driving either to rich people shindig or a party where the drink of choice is apple juice or coolaid.
FM2…“Ah, LaLa, Ah, LaLa You’re so cool” or something of that nature.
Outside FM
Project Gotham - Sir Mix a Lot’s “Resonate” was the shizzle
For some reason I still get that song stuck in my head.
Never been a fan of the forza sound tracks…
GT2 had an excellent soundtrack.
I play Forza since FM3 and I think that FH1 had the best soundtrack, there was great songs like Blue Monday, Leves Skrillex Remix, Cinema Skrillex too, Reaching Out, Lick The Raimbow, Show Me A Sign, Paddling Out, Something Good Can Work, Dont Stop Colours of The Wall, RU Mine?, Lonely Boy, Farewell to The Fairground
Forza 6 has the best overall soundtrack. Both the menu music and the in-race music are fantastic.
Forza 3 and 4 also had excellent menu music, but forgettable race music.
Forza 5 was way over the top and didn’t really fit the game at all.
I’ve never been a fan of the popular music in the Horizon series.
to be honest maybe horizon 2 main menu or motorsport 5/6
First one is always one to remember because it was a sure hit. The game was just something new to a racing genre putting music festival around cars ( yeah maybe juiced 2 too but it was more like street legal party than festival 
) I´ve never played it yet I watched so many videos and enjoy listening to that music in my real car to this day but for me one that had best OST was the 2nd one I have all of them in my car´s playlist and even thou I love 1st and 3rd I´m always smilling when I hear the track from 2nd one 
And 4th is close like really close there are some tunes which are catchy and would be awesome to hear when I´m cruising in real life 
FH2’s classical station was the best for me personally. The newer games have some neat pieces, but FH2 had the best overall selection IMHO. Can’t speak to the other stations, don’t care for the other genres of music.