Cute strannik (smile).
You need to know how big your pool is, so you can see what size cell you need.
Then you need to know how much you are willing to spend, and what options you want for your money.
Where I waited for a local company sale and bought the cheapest thing I could get by (but still over sized) with for my size pool.
Been working great for 3 seasons so far.
I do love the salt in the water. I do not use goggles any longer as the water does not affect my eyes, and my skin and hair does not feel all dried out after a swim. But you do not need a SWG to gain those same benefits, only salt.