I been all for a bonus to medals for a long time and the countless times its been asked for.
That said yes any bonus should be very small and almost nothing at all for example a pvp medal should give 1-5% damage going from silver to ruby (I suggested this before diamond and feel diamonds should get a bigger bonus perhaps 7.5% damage for this example) so small they dont help at all but simply add another reason to get them.
And suggested before here are the bonuses I thought would be good for the cooresponding medals, all go from bronze to ruby,, diamond should have a bigger reward imo
Bounty master gives 1-5% more atk
Recruiting= 10-50 bonus FSP
Top 100= pvp protection for 24hours to 5 days
Top player= +1-5 exp gains
Top hoarder= +1-5 gold gain
Loyalty =100-500 loyalty tokens
PvP dom = 1-5% damage
SeS = 1-5% permanent light foot!
adventurer = 1-5% HP
Annual service is a unique one I feel there should be a gift for your FS birthday perhaps a leveling pot that increases to something close to a global chest for diamond,, it wouldnt hurt anyone
Monthly top 10 is also a unique one,, nothing should be added on this till you achieve one year in FS as its way too easy to get this medal in lower levels. After a year perhaps something like prestige where you get a special buff you can activate when you get the medal giving 1-5% extra exp for one hunt.
pvp arena= 1-5% def and armor and is included in arena stats
Titan, like Ses should get 1-5% lightfoot so a diamond titan and SE hunter can get 10% LF total
Treasure hunter = 50-1000 loyalty tokens,,basically a free key of the type you got medal for
Guild loyalty= a deposit of 10k- 1mil is made in your name directly to guild bank
global quest= a free global doubler going from the lowest to highest buff level for each medal tier
global quest top 100 is possably the hardest one to get in the game and so deserves a big bonus but given they get a lot of rewards already I suggest 500-5000 reserve stam (getting top 100 diamond is gonna be epic and deserving of 5k stam)
pvp shasher= another 1-5% damage
phoneix= already got lots of reward so maybe just something like 1 backpack space per medal level (this means you have the phoenix come back and get the 50 levels and 20 days so it isnt exactly a easy medal)
Fragmentor = either make it a joke and give 1-5 common items or maybe 1-5% cheaper repairs
Of course your suggestions are great too but thats what I would offer for medals and yes I made sure the easiest ones got the least reward while trying to keep them a bonus related to what the medal was about