Well what else to pick as mythic feat for a ranged single class slayer? There aren't a lot of choices
I broke down three screens of good ones somewhere upthread.
Extra Mythic Ability (Cleaving, Distracting, Ranging Shots are all good, and that's before getting into Inspiring Leader (good to put on noncaster), Last Stand, Unstoppable, Defensive Study (not as necessary ranged unless you're Snap Shotting), and Ever Ready again with Snap Shot. Mythic Feats if you want AB you've got Mythic Rapid and can always use the Mythic Feat side for a regular Feat, so you're spending equivalent of two Feats for 3 AB. I like a Mythic Skill Focus later to take ten on a key skill or Mythic Save to get advantage on weak Save.
Mythic Improved Initiative is probably the most subtly powerful Mythic in the game. Lets you get that first Sneak in on a Flat-footed target to establish Studied automatically. Makes up for not having Uncanny Dodge (if you don't take it).
Archer's going to be boring if you're playing it one-dimensionally but Slayer sets up well to be your Scout (replacing Aru) with very high Stealth, Perception, and Trickery. You can use Mythic Feats to eliminate RNG and the Defensive/Snap Shot Mythics let you open combat from a forward position and take all comers instead of hanging in the back.
I'm on TTT now which gives a wealth of options but there's room to get creative on game-changing stuff even in vanilla and Mythics are pretty backloaded in any case so the stuff that matters most is in first four Mythic choices.
This is interesting. Accidently retrained Angel (and forgot to memorize Angel spells so no Divine Favor) into Underground Chemist 4/Grenadier. Meant to do Trickster.
The regular Grenadier Bombs don't get Sneaks/Debilitating but the Alchemical Weapon Ability on Grenadier does and can be stacked onto the first Bomb you throw every turn (Edit: looks like it doubles every Bomb you throw, Ghost just died too fast). Grenadier has Martial Prof and UC has Finesse/Finesse Training so can play as melee character (with Feral Mutation) then switch to Bombs for Touch attacks. Alchemical Weapon can also be used with weapon attacks if you buy enough Bombs. Looks like it pulls them automatically out of inventory too.