Well, The battle is CLEARLY between Feraligatr and Typhlosion. Now i will quickly run over the differences.
Feraligatr @ Life Orb or Expert Belt
4 HP / 252 Atk / 252 Spe
(Adamant)
- Dragon Dance
- Waterfall
- Ice Punch
- Earthquake
This is the best set for beating tough trainers (Elite Four, Gyms, ..)
But! If you want a more type covering / versatile set for overall fights, this is the one:
Feraligatr @ Leftovers or Expert Belt
4 HP / 252 Atk / 252 Spe
(Adamant OR Jolly)
- Ice Punch
- Waterfall
- Earthquake
- Superpower
However Typhlosion can be a good choice too:
Typhlosion @ Expert Belt or Leftovers
4 HP / 252 SpA / 252 Spe
(Modest or Timid)
- Eruption
- Flamethrower (When health is low)
- Solar Beam
- Focus Blast
The Final Conclusion: Feraligatr is the best choice as a starter as it covers more types which makes your game much easier.