I want to be able to decide which trampoline node I want to use because some of them seem to work more efficiently than other.
By more efficiently, you mean faster?
If I need to increase the receiving capacity of one channel, I want to be able to select it to send my next payment, same thing for a channel with a low sending capacity.
I see. Unfortunately, no. It isn't possible from any user interfaces, as far as my lightning software experience goes. That's rather a specialized setting, only accessible if you dive into the source code. If you don't do that, which I presume you won't, your best course is to complete the payment using any channel and rebalance afterwards using a plugin. In both C-Lightning and LND, there is such plugin[1][2], but I'm not sure about Electrum.
[1]
https://github.com/lightningd/plugins/tree/master/rebalance[2]
https://github.com/C-Otto/rebalance-lnd