I have been shooting air guns long before I became hot and heavy with "powder burners". I will give you my 30+ years and two bits that is not worth two bits on the subject.
If you want to use your air gun as "off season practice" forget any spring air rifle, they are about as different shooting experience then you can get. They push a pellet with air but that is the only thing they have in common over other air rifles. For real practice MSP, PCP or CO2 guns are going to be the most close to a "real" rifle.
Pumping a PCP by hand sucks rocks, no way around this it sucks, it may look like a bicycle pump but trust me it is far from it. Buy a compressor. I am on roughly year 6 of a yong heng Amazon special, fill tanks with it roughly monthly, shut it off when it hits 55C, and let it cool down. Feed it distilled water for cooling, and it has given good service with just oil changes for that long. It runs three filters, and that does take a minute for them to come up to pressure, but I have never had a moisture issue.
In the long range world as I understand things you could have the best equipment out there, but if you have crap ammo it means nothing, pellet guns are 10X that, you need good ammo and that is not found at walmart. Below is a 50 yard group shot off a "rest"...if you can call a 1960's card table a rest. Two different pellets, same weight just different makers, it is clear what the gun likes, and the three flyers are likely that card tables fault....at least that is my story and I am sticking to it. This is a 10 round group through a first gen Gauntlet.
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That is a bone stock gauntlet with a cheapo Tasco scope on it....might be a centerpoint, key here is CHEAP. Not a bad 50 yard group IMHO.
To stay on that cheap topic, I have a $89 Walmart crosman 2100, actually branded Remington, that is about as cheap as you can get, it will give like groups at 25 yards, they key is to find a pellet your gun likes.
I have not looked in a long time, and can't remember the name but one of the online outfits made a pellet sample pack, that was across the board, had JSB, H&N, RWS, you name it they had a few of each in this one "kit". Dog if I can remember who it was. But I know people like JSB have sample packs and that is a good place to start. H&N is very good down to the .0x IF I remember correctly, and I can tell you it does make a difference.
I will also say that if you take your time, and work with your rifle you can get some very good results without having to spend big money. IMHO the area where these "cheap" airguns are let down is in the trigger area, most have just horrid triggers, some can be fixed, some can't. Some like a Mrod have some very easy fixes that are all over youtube, things like the "lawyer spring" are easy to.....adjust I guess I will say.
They are quite fun, and I think do keep you sharp, the thing that a PCP will take away from you is off hand shooting, these things are porkers. If you want to do off hand I would suggest a CO2 gun as the weight is so much less. Hammerli make a great CO2 gun, and I have had great luck with any of the QB78's that are out there including those moved to PCP like the Chief.
If you want something fantastic to work with indoors, and would be the most "easy" thing to hand pump, look at the benjamin maximus, I bought the euro version so limited to 12fps, and it is a fantastic little gun. Easy to pump if needed not a "real" high pressure fill, will shoot all day on one fill, and it is so straight you would think it is on a regulator....it is that flat and steady....it is also pretty light like most of the QB type PCP rifles.