high sitting optics are kind of the name of the game with the ak platform, that being said I use the AK master mount. it replaces the trigger pins with its own threaded mounting pins to attach a side plate to the rifle. so far its been a very good solution! the plate has remained absolutely solid. i also appreciate the fact that because it uses the trigger pins the side plate sits lower than it would on a standard side plate on a factory rifle so the optic ends up being a little lower to the dust cover. other than the master mount id say the ultimak is the way to go (this is all assuming you are not willing to rivet on a traditional side plate) here are some pros and cons just off the top of my head after some time with the master mount.
1. easy alternative to riveting on a traditional side plate
2. optic sits slightly lower than a traditional side plate ( although probably not as low than on an ultimak rail)
3. optic is in a more "traditional" position on the rifle compared to using something like an ultimak
4. optic stays cooler as its not contacting the rifle directly.
5. no need for a trigger pin retaining pin\ plate as the replacement pins for the master mount "bolt in"
1. changing the trigger becomes more of a bitch so make sure you have the one you like in there before installing the master mount.
2. you need to also buy a side mount rail and they can get pricey if you go for quality ie. RS regulate, GGG ect.
3. slight bulk added to the rifle with a side mount compared to something that attaches directly to the top of the rifle.
4. possibly not as much of a "proven" design as something like the ultimak. i cant say exactly what kind of steel the pins are made of and theoretically under very high round count its a possibility for them to oval out the trigger pin holes although ive done a good amount of "interneting" for this and haven't seen anybody mention it as an issue.
In conclusion the master mount has worked well for me in my use with it on my rifle and i dont have any issue recommending it to anyone. like i said these pros and cons are just real quick off the top of my head so take from them what you will. also stay far away from railed dust covers, in my experience they do not retain zero. hope this helps!
Side mount is the easiest. Anyone who has the slightest idea how to gunsmith on AKs and has the rivet tool can install one in minutes. It is tall, but reliable, the mount rail isn't too obtrusive if you do not want it later, many options for what to clip to it, including mounts integral to the scope/RDS (if you go Russian) to keep the mass/height/snag down.
I know a number of folks very happy with the Ultimak. Clever RDS selection gets you to co-witness, so I hear. Yes, gets hot so plan accordingly. Don't touch the aluminum above the lower handguard.
A few similar front rails also exist; Zenit for example makes some used by the Russian military / security services, but as much as I know Zenit electro-optics are fine, I know no one personally who is using any of the rails so have no further data. They do have US distributors.