^.
We all know shyvana isn't the best at it, the question is...Who is?
Lee sin with his flying kicks over walls?
Trundle with his uncatchableness?
Nunu with his double smite?
Udyr with his AoE of doom?
Insert champion with his pwnage?

The better player is

The jungler that has map awareness and knows where to ward.

Trundle's terrible, what are you talking about?

~SSoTP

Player = 60% of counter jungling
Team = 20%
Champ = 20%

Shaco

He doesn't spend his time stealing your buffs like others though, he spends his time killing you in your own jungle.

Lee singah

Lee sin, Shyvana, trundle Shaco are the best counterjungles in my opinnion, mostly because you absolutely cannot fight these champions early game if they invade you, they all do crazy damage from level 1-4ish and all have very high mobility+slows(well shyv doesn't have a slow).

A good counter jungler needs to be able to do certain things to be effective.
1 - Kill fast
2 - Escape fast
3 - Be Scurry.

Theres a reason you don't counter jungle people as fiddlesticks for example lol

if u want invade. u need to know:
1- All enemy champions.
2- Where ur enemy jungler are at any time.
so u need to know.
-repown.
-where he start
-wath min items he need for jungle.
-how many pots he have before to invade
-where is him at any second!

a support with CV can rly help u with that.
imo the best one is xin zao in lvl 3 u can gank ur enemy in lvl 3 and rape his €|@#||@. =) before he take his red. and u can go out using flash on baron on dragon before hole enemy team rape u .
so at min 4 u have 2 red 1 blue and 1st kil. and the mos timportant ur enemy ungler lost blue and he lsot exp from red.
but take care with other counter

so u need smite+flash.
i do it also with Noc or rengar ( best of the best for that but much more harder )