My go to pellet in .177 for ratting are H&N Hunter Extreme, a light heavy weight providing power from my barrel at upper 11's dead accurate to 35m they fly reasonably fast and do an amazing amount of damage to a rats head.
My barrel isn't pellet fussy with only having found a couple of pellets that it doesn't like JSB Hades, BSA Goldstars, virtually any pellet available will do the job if you do your bit.
I have used loads of different pellets over the years with good success, don't dismiss wadcutters for ratting, ones i have used Bisley Practice, RWS Hobby etc. in fact any pellet that is accurate through your barrel at the range you shoot rats at will do the job providing you do your bit.
I suggest you try some samples of what you like, find one or hopefully lots that group well at the ranges you shoot at and use those, you can always try others too, a bit of pellet testing is in order i think mate.
No other way really than to test lots and find the ones that suit your barrel as others have also said, good luck with your testing, here is a little list of pellets that are good in my barrel and do the job on the rats.
H&N
Hunter Extreme (my go to pellet)
Terminators
FTT
Match
BISLEY
Magnum
Pratice
LRG
JSB
Exact
Exact Heavy
Exact Express
Exact RS (if loaded single, not in mags)
Predator Polymag Shorts
Match Flat Head
AIR ARMS
AADF
AADF Heavy
AADF Express
AA Match Flat Head
RWS
Superdome
Superfield
Hobby
RIFLE Premium Series Domes
RIFLE Premium Series Flat Head
DAYSTATE
FT Heavy
FT
Rangemaster Sovereign
Kaiser
FX Airgun Pellets
8.44gr
10.3gr
SMK Spitfire old type (after a clean and degrease)
SMK Spitfire new type after a clean and degrease)
WEBLEY VMX Pell
WEBLEY Accu Pell
QYS
Domed
Streamlined
SNOWPEAK Domed (after a clean and degrease)
ELEY Wasp
New Wasp
And probably some others that i have forgotten to mention.
H&N Excite Econ ll, Geco, Norma, BSA Silverstars and a few others still to try, always more to try as you never know what are good unless you do.