Just my thoughts on bits and pieces in the class
Eidolon Stats:
The ability scores are a bit different on the eidolon
STR normal
DEX normal
CON doesn't affect its hit points just fortitude saves
INT doesn't affect its number of skills, just skill checks
WIS doesn't effect initiative, but perception, will saves and skills
CHA only effects skills
Aiding the summoner skill checks is useful, but only important in combat as others can do that as well.
Eidolon Options
Angel
Slightly more Wis than INT which is a bonus.
Good damage is useful. Travellors aura sounds nice but it doesn't work in tough fights(against equal level opponenets) which makes it a zero to me
The mercy spells are useful, but really level 17 is a bit late for these to be special.
Beast
Slightly more Wis than INT which is a bonus.
The charge maneuver is very good +1 to hit plus action efficient.
Primal Roar is pointless. The summoner is likely better than this for the price of a skill feat, and you are 4 points of Cha behind
Whirlwind Maul is a good maneuver like Whirlwind strike. Probably important to have reach for this.
Phantom
Dutiful Strike is a good reaction. Though they should probably attack the Eidolon instead
Steadfast Devotion is a nice save bonus
Dedication Aura a small defensive aura of resistance. Very minor at this level
Dragon
A weak breath weapon. Probably only good if the enemy is vulnerable or you can line them up. It nice that is gets better later
The frenzy attack is 3 attacks for 2 actions. Good but the MAP is normal. The breath weapon is not strong enough for the bonus recharge to be a concern.
I think I like the beast best.
Comments on selected Summoner Feats
Distracting Summoning Spell - Nice triggered extra attack - but you only have 4 spell slots so if you really want to use this you need to get more somehow.
Tandem Move - Compulsory and crowds out other feats at this level
Hulking Evolution - seems pointless for so long
Ostentation Arrival - doesn't appear to be any saving throw against this damage. Which makes it a cool ability. Needs more spells to be great though. But still good for when you bring your Eidolon in.
Summoner Shield Evolution - carry a shield and raise it instead
Flickering Evolution - is this trap detection mode - otherwise it seems pointless
Greater Magical Evolution - two spell slots for your Eidolon - nice for utilities or pre buffs - but the Eidolon has your reasonable casting skill so you could do anything with this.
Ranged Evolution - nice but a bit short range. The Eidolon is probably better off with a cantrip
Boost Summons - only if you have more slots
Protective Bond - nice defensive bonus
Transpose - useful but narrow
Summoners Call - nice. But you can do this most slowly with unmanifesting it and remanifesting it
Transmogrify - probably the best way to take those more situational lower level feats
The rest seem good and fairly obvious with the exception of Eidolons Avatar - not sure its of much use except for a free successful commune. Wouldn't be my choice for a capstone.