In "the old days" Selva were well below the price and reputation of the major brands. Often based on an older generation design (Yamaha's I think) than others of the time and usually just a bit more crude and noisy.
But some folks appreciated their value and got on fine... so if you find a good one you might too... but they have to be very cheap.
Moving nearer these days I think they might have caught up with supplying near like for like models of what they copy for any given year.... but still need to be bought cheap.
Parts are mostly harder to find than the popular brands.
Edit: Just found the website of the current UK supplier. Prices above that of Honda, Suzuki etc which is daft.