Long gun recommendations
...the only long gun I will get so it needs to be able to fit a generalized profile.
Ideally this gun needs to cover the following points:
* Easy to maintain under less than perfect conditions
* Handle at least small to medium game
* Easy to find ammunition
* Able to mount optics is a bonus"
This is a tall order.
In the order presented:
...maintain... This is most main stream rifles. Otherwise, they would have been dumped by the shooting public.
...small to medium game... Medium game will limit rim fire rounds. Most everything else will handle this option. Although, too much weapon/round will not leave much to eat.
...Easy[of]ammunition... This brings the choices down a lot. Depending upon your area some of these will change. Biggies are: .223/5.56, 7.62X39, 308/7.62, 30.06. Area dependent, add: 30.30, .243, .270, 8MM, 303 Brit and several more. Their are many options but I would go with one in the first grouping.
...mount optics... I can't think of one rifle that some type of scope isn't being mounted on. Some are much simpler than others.
As you have not included reloading, I will do the same.
Not knowing your determined needs, I can only splatter about.
A bolt action made my a better known maker in .223/5.56 or 308/7.62 would be a good option. Used is good.
An AR15/M16/M4 type in .223/5.56, if self protection may come into play.
(I don't care for them, but) A 'SKS' or AK type in 7.62X39 is less up front cash.
As there are two of you to arm, maybe a bolt in .223/5.56 and an AR/M4 in .223/5.56. As you don't list loading, go with the 5.56 chambering or one of the mix chamberings like the Wyled to give full supply options in ammo.
Study, read and gather as much information as you can before making your decision/s.