Corsola as a starter made FireTRUK a possible deck... Trust me, it's nowhere near as effective if you can't swarm basics out quickly. THAT is the key point for Typholosion. And unfortunately, we get Pachirisu in Great Encounters, which eliminates Typho's advantage.
Theoretically, you shouldn't be relying on Typho to attack, and neither should you be relying on Blazi for attacking. Of course, both have attacks that Magmortar could pair quite well with (Blaziken: 10 to all pokemon on bench. Don't forget GE counterpart can act like a mini-Magmortar LV.X if needed, nor forget Blaziken EX for a quick 100 damage no matter what or Fighting Type Drag Off to counter stuff like Dugtrio that prevents Bench Damage. Typholosion: Discards DRE. More situational, but can win Gallade matches for you). Attacks are not relevant, 'cause both are useful. If anything Blaziken line has more options to set up into, and actually wins that department. HP is not relevent, 'cause neither will be attacking... The 110 over 100 IS big in the mirror match, but Delcatty is vulnerable on your bench as well, so it's not like Blaze is your only sitting duck on the bench (and again, you can use Blaziken GE to double up on sniper duty and eliminate THIER Delcatty lines... Actually really quickly, for only 3 fire energy). Therefore, the only part that is relevant is how easy they are to set up. Pre Great Encounters you can either use Cyndaquil and be able to Corsola for 3 pokemon, or use Torchic and be stuck with only 2 pokemon from Corsola (might as well Tauros at that point). After GE, there's no such restriction on Torchic. Fun, eh?
Now to relate this to the conversations of FireTRUK vs. MagKiss...
Does MagKiss have a secondary attacker that's as beneficial as either Typholosion or Blaziken? Last I checked... Togekiss was doing reliably 40 for 3 energy (ew, that's inefficient). Of course, you can get heads to do 70 damage, which is... Much weaker then Magmortar. Why are we attacking with Togekiss AT ALL? The Firestarters make up more then an emergency plan; they can abuse secondary effects to go places which Magmortar on his own might need more help to do. Togekiss can either do inferior damage to Magmortar, or heal itself. Why are we even bothering to heal Togekiss? I thought we wanted it dead, so we could recycle that? Either that, or scoop it up. EITHER WAY, you're not in any sort of mood to care how much damage is on Togekiss. :/
Togekiss can't even do anything interesting with it's basic or stage 1. If you try to use the delta versions (which actually have okay attacks, though their HP fails at life), you can't due to water energy requirements. Torchic can burn pokemon for 1 fire (no flip~), Cyndaquil (not d) can do 10 damage for no energy, Quilava can do 40 for 2 energy unlike Togetic's mere 30 (which won't 2 hit KO many stage 1s, unlike Quilava), and Combusken can do 60 damage for 1 energy (Though it'll take a turn to set up the first 60). It'd be one thing to have failure attacks if you had better HP and free retreat, but Togepi and Togetic have same HP as Torchic/Combusken, and MORE retreat cost then Combusken. What's wrong with this picture...?
So... FireTRUK gets more benefit from the secondary line's powers then MagKiss... FireTRUK has better secondary attackers then Magkiss.. HECK, FireTRUK has a better starter then MagKiss (You can't argue that Pachirisu into having a full bench then a really easy Delcatty drop is a set up possible in MagKiss, unless you WANT to make Togekiss worthless. To make Togekiss most effective, you'll want a Fishing Engine, which works a lot better if you sacrifice your starter for the cause :/). Seems better for Magmortar in just about every way. At least to me it does. Maybe my bias for Typholosion in general (as much as I hate to admit Blaziken could be better if you're bulking the line up significantly) is skewing this analysis?