I know that some topics have already been opened but since I have a lot of experience in this field since i ve been there two years I would like to share this with you, maybe it can be helpful.
I more in SNK (KOF) than CAPCOM so i will write something about KOF first and then go to your majesty SFIV or CAPCOM in general.
KOFs are everywhere! can’t find any arcades without at least one cabinet with KOF2002!
Yau Ma Tei: I love to play in an arcade called GAMEZONE/GAMEPOWER (dont remember very well) in Yau Ma Tei near Temple Street (in a street with karaoke and mahjong) where a credit is just 1HKD, which means just 0.10!!! fucking cheap! and the best part is that there are something like 4+4 cabinets link to each other (KOF2002), then 1 cabinet 1p vs 2p (2002), then 1+1 cabinets link to each other for KOF98, 1+1 cabinets link to each other for KOF2002 PLUS (hacked version)… no Capcom games in there though… some Gundam games, Initial D, Dragon Ball and the cabinets with drum and guitar… I love that arcade, to me it’s the best for KOF2002… cheap as hell and with so many cabinets and you can find anytime someone to fight with! Of course if you are looking for some Capcom players you won’t find them there!
Yuen Long: There a few arcades in there. In the first one there wasnt anything interesting, one awful kof2002 cabinet and then other games I’m not interested in (no capcom game). Then I went to a big arcade near a whore building in a square (just go here 2-6 Yuen Long Pau Cheung Square, you will see it). Very big and with a lot of cabinet… since here mostly like fighting game I will just tell you which on you can find there:
-1 cabinet for SF3 third strike (1p vs 2p)
-1 cabinet for KOF2002 (1p vs 2p)
-1 cabinet for KOF2002 PLUS HACKED (1p vs 2p)
-1 cabinet for SVC CHAOS (1p vs 2p)
-1 cabinet for KOF98 UM (1p vs 2p)
-1 cabinter for GGX RELOADED (1p vs 2p)
-1 cabinet for SENGOKU BASARA X (1p vs 2p)
also here 1 credit is very cheap, dont remember if 2HKD or 1HKD…but still damn cheap! Well to me it wasnt that great since there were just a few kof cabinets but still it has a good atmosphere and you can find everytime someone to play with.
MongKok: shopping,eating,fucking and then arcades… that is what you can find there lol since it’s not a xxx website I will tell you just the arcade i ve went to!
It has 2 floor but what you’re looking for is at the first floor, near the public toilet (in a square with a strange clock):
-1+1 linked cabinet (no LCD) for VF5 (2HKD for 1 credit)
-1+1 linked LCD cabinter for VF5 (3HKD for 1 credit)
-1+1 linked cabinet for KOF98 (1HKD for 1 credit)
-2+2 linked cabinet for KOF2002 (2HKD or 2HKD (dont remember) for 1 credit)
Also here Capcom fans wont be satisfied… SNK and SEGA will be though ghgh …
Good atmosphere and plenty of ppl, you will find enemies everytime you want
Tsim Sha Tsui (located near 42-44 Granville Road, there is big logo and then go down the stairs): there is one called "GAME sth " with 3+3 linked cabinet for KOF2002,2 cabinets 1p vs 2p for kof2002 and then 1 multigame with plenty of capcom games (1p vs 2p) … 1 credit=1HKD … small but worth a try
Tsin sui Wai: in the Ginza shopping mall there is this arcade with 1+1 linked cabinet for KOF MI2 (1credit=2hkd) , 3+3 linked cabinets for kof2002 (1credit=2hkd), 1+1 linked cabinets for DragonBall (1credit=2hkd) and then a 1 multigame with plenty of capcom games (1p vs 2p) (1credit=3hkd)… small but very crowded at night so you can find a challenger anytime for kof2002!
Prince Edward MTR C2 Exit: a majhong/poker machines arcade with ONLY 1 kof2002 cabinet 1p vs 2p 1credit=2hkd… cheap but NOT worth it 
and now for all the SFIV fans… here a list of arcades that have that game!
Mongkok (BEAUTY FOREVER near exit B2): despite the one I told you about before, in this one you can find plenty of SFIV cabinets linked to each other … LCD cabinets and NORMAL cabinets… 3HKD for a credit, tons of ppl so CAPCOM fans will be satisfied very much, for SNK supporters there are 2+2 link cabinet for KOF2002 and 1+1 link cabinet for KOF98 … at the end a good arcade for both players/fans.
Lai Chi Kok (POWER CITY near exit A): i found an arcade with just 1+1 cabinet LCD for SFIV with tons of ppl line up for a play (1credit=5HKD)… then 2+2 linked cabinet for kof2002 and 1+1 linked cabinet for kof98. Not much but very crowded so be aware that for play you might have to wait a bit … is it worth it? if you like to be watch and watch other playing maybe yes.
I love arcades in HK … packed with ppl,cheap and good games (i’m more in kof than capcom)! but hey…do you want SFIV you will find it without any problems 
ah yes nearly forgot… on the 15th of January has been released BlazeBlue and in the near future as soon as it get released in JP there will be available KOFXII !!!
if you want other names i can give them to you with pics.
Now CHINA… well I went only to FOSHAN and find just one arcade in there (Zumiao Commercial Street in a shopping mall). It was a biiig one with a lot of old cabinets (SUPER HANG ON was still there!!! lol ) and new shooter and dancing cabinets. The only fighting game I found there were:
1 cabinet kof 2002 HACKED(1p v 2p)
1 cabinet kof 99 (1p v 2p)
1 cabinet kof 2000 (1p v 2p)
1 cabinet kof 97 (1p v 2p)
1 cabinet kof 97 HACKED (1p v 2p)
cheap and if you dont have anything to do during your staying there give it a try but … i dont know …maybe it was cause i went there in the morning and there was nobody…
