I don’t know how familiar or not you are with “dead keys”, but the way they work is that you type the accent first, and then the vowel (the fact that in your case you use the AltGr key to do that adds an additional step/layer of complexity… AltGr+dead_key, then release AltGr, then type the vowel… all without seeing the accent before it is fully formed).
Please specify which language you’re interested in, because it’s quite likely that there might be a particular keyboard layout better suited to your usecases. The German and “French (Canada)” keyboard layouts are examples of such layouts that allow typing dead keys accents without the AltGr key. Some other layouts allow typing accented letters directly (without dead keys at all), with less flexibility. So it really depends what your needs are, how far you’re willing to deviate from the English QWERTY or Dvorak, etc.