Some notable things the different options would give (not counting evasion)
Monk:
- 1 bonus feat (not 2, since you miss out on the level 20 bonus feat from arty list)
- spending 2 AP (1st core thingy in each of henshin mystic & shintao trees) will net you +1% fire & force crit chance, a bit of spellpower for each, +10 positive spellpower to boost those handy admixtures & 5% healing amp, all of which are never bad things
- up to 2d6 sneak attack via ninja spy tree
- NOT a stance, as rune arms will uncenter you.
Rogue:
- lose 1 feat
- up to 3d6 sneak attack from class & enhancements
- Arbalester, to increase the PBS & sneak attack distance.. ok not much but it can help.
- extra crossbow training enhancements
- improved traps, if you like using them