Depends on whether or not the TES setting is treated realistically. Ie, dragons don't land so they are vulnerable to ground forces, instead keep breathing fire from above from where people can't hurt them. Spells like fireballs will actually scorch your face, rather than just tickle your HP bar. Etc. I will assume that the setting is being treated realistically.
After escaping Helgen, he'll probably join a side in the civil war. The Imperials tried axing him so he'll probably be inclined to join the Stormcloaks, but there are compelling arguments for him joining either side. Even if he doesn't join right away, if he tries settling down in a village, the village is going to get caught up in the war and he'll probably get involved anyway. After the Skyrim Civil War ends, he'll almost certainly wind up going after the Thalmor next.
- He possesses the power of the Dragonborn only, magic, shouts, the whole shebang for a starting chosen of Akatosh.
Even with this stuff, it will be very easy for him to die in the TES world. Defeating Alduin and winning the war will be difficult but not impossible.
- He gets the same as above but with the Attack Titan as his racial power.
He ROFLstomps through the TES world. With his regeneration, it is extremely difficult to kill him. He can survive almost all melee wounds, even getting beheaded. On the ground, he can use his power to generate a flesh shield to block a strike against him. And he can transform into a near invulnerable giant monster, which will be really useful against dragons. He will only really be in danger if the dragons go for his nape. However, while he won't easily die to dragons, he still doesn't really have a way of hurting them (unless he can cast spells and use shouts while within his Titan).
- He gets the Attack and Warhammer as his racial power.
With the power of the Warhammer Titan, Eren can now launch ranged attacks at any dragons within visual range. He can also use hardening and make himself invulnerable to pretty much anything. Complete ROFLstomp of the setting.
- He gets everything that both the Dragonborn and Founding titan has to offer.
He's already ROFLstomping through the setting but this just makes it go faster.