In my almost-two-decades of fishkeeping, I've never found the perfect siphon.
Currently, I've got the JBL Aqua-Ex 10-35, the Marina Easy Clean and the Bi-Orb Cleaner Pump. For my small tank, I find:
* the Marina's cylinder too long and not flexible enough to move around and tackle corners [other brands have been too flexible, though];
* the JBL's internal grid that catches debris catching too much plant matter and which blocked the water from being effectively sucked up, so took it out but then found the flow was too fast and 60% water changes were happening before I knew it [in a larger tank, though, the timing may be similar but the amount of water taken out may be proportionately less];
* the Bi-Orb's squeezing self-start pump difficult to operate - my grip strength isn't strong enough, and, when getting an able assistant to operate it, the flow is way too fast and 60% water changes were happening [cf above comment about proportion of water removed in a larger tank].
The best method, I've found, has been to detach the cylinder / wide part of the JBL Aqua-Ex and simply use the tubing itself - this can be manoeuvred by hand into the corners, gets into small nooks and crannies, and the flow uptake is spot-on correct. [I used to start the siphon by sucking on it but, after too many mouthfuls of water, have now trained myself to start it by submersing it in the tank beforehand or even filling it via the tap and then blocking each end with my thumbs before starting the flow.]
Having said all this, my recollection from having gravel many years ago, is that faster flow uptake is a positive aspect in that it sucks debris up from between/under the gravel pieces, so, of the 3 I have, the Bi-Orb one might be the best option in your case as the grid holes at the end of the cylinder part are small enough not to suck up pieces of gravel but still provide the stronger flow uptake.
Hope that's helpful - apologies for having no experience of battery-operated ones, etc.