Do you ever get heavies or snipers when you recruit? I’ve started over 4 times now and I only ever see assaults at havens, and then a bit later some specials (techs, priests, melee, etc). I’ve yet to see an actual heavy or sniper though…
The bulk of the recruits seem to be assault class. I have picked up mostly heavies and snipers from Jericho havens. Berserkers and Priests from Anu and Infiltrators and snipers at Synindiran Havens.
I have seen recruits of all classes, but heavies do seem to be less common. It varies game by game though. I’ve started a new run tonight, and so far I’ve gotten quite a few sniper recruits. It’s all random I think.
I can confirm I managed to recruit Heavy (x1), Snipers (x2), Assault (x1), Techie (x2), Anu Priest (x1), Synedrion Ninja (x1). So all are possible to recruit.
I could be wrong, but I think I saw my heavy being recruitable from an elite recruiting facility at a New Jericho haven. If you’re not allied to New Jericho you might have a harder time recruiting one, seeing as both Synedrion and Anu rely less on such soldiers.
Or I could be completely wrong and you’re just unlucky 
I make my snipers by second classing them. The perks from the assault class can actually make snipers even more dangerous.
I already realised that HEAVY snipers are the way to go, because they can jetpack onto the best high ground firing positions and stand their ground their in heavy armour even if there is no cover. From there, just spam quick aim double snipe every turn. You can also strap a missile mount onto them and snipe+rocket uses AP effectively.
With Assault, dash is 4 willpoints (jetpack is 2) and doesn’t get you as far. I would say pure class or heavy snipers are the way to go.