I'm a huge impregnation fan.
MoR 0.8.4.3 - I definitely don't recommend this for impregnation fans. It's a well made game etc but it is not impregnation focused. You basically fill a girl up with semen and chances are she'll be pregnant the next day. 0 interaction/signifiance of pregnancy. 0 pregnancy talk. In general, I find the game itself is lacking in sex content. It's moreso a nice adult RPG than a sex game.
Lab Rats 2 Reformulate Mod is my favorite at the moment. It's sandbox with multiple random women attributes being created (different sexual preferences etc) per female. There are instances where a girl would ask you to take off your condom before ejaculation just so you can knock her up, there are instances where a girl might have a breeding fetish and ask you to knock her up on the regular, there's a mini story where an employee's husband is infertile and she becomes your breeding stock, there's a Love Interest who has a culture centred around no-condom sex and children,
Jwright989 there is the possibility of banging your mum/sister while they're asleep and knocking them up in their sleep (I found high sluttiness and preference for vaginal helps here since they're 'so accustomed' to it). Honestly the game has a lot of focus on impregnation. The best way to play the game is to impregnate women because one of your most vital currencies is 'clarity' and the best way to maximize clarity is via creampies.
X-Change Life (Kokopelli's Servant Mod) would be a close second. Unfortunately I don't care for transformation/gender swap etc etc but funnily enough, the bar girl system in the game is very nice for straight male impregnation lovers. In the base game, you have to pray the girl doesn't take birth control but with the Kokopelli mod you can manipulate their birth control and you can be knocking up a dozen/2 dozen women on the regular. Unfortunately the system itself is still very minimal since the game focuses more on any and all content other than straight male playthrough. And also unfortunately, the Kokopelli mod creator seems to be pushing the mod in a 'sissy' direction, but we should respect their creative directions. Thankfully the cheat menu is only a click away to undo all the forced sissification the game tries to push on you. I think a standalone game with the bar girl concept that focused entirely on just picking up girls at the bar and knocking them up would be super awesome.
edit: Agree with
guyman1337 regarding Summertime and Love/Sex. Summertime Art art and character designs take away from my playing experience. Honestly if the game was Honey Select or AI art I'd probably enjoy it more but that's just my preference.
Love/Sex is pretty awesome but the event triggers are horrendous and I feel there isn't really any "impregnation talk". You just get the option to go condomless once a girl is ok with getting pregnant. I don't remember the love interests changing their dialogue after they're pregnant either.
Summertime Fans would probably like Taffy Tales I think. I get similar vibes from the game