What an adorable dog! I would buy a much shorter sofa in a similar style, but please make sure you move it away from the TV by about two feet. Right now your living area looks tiny. You should now have room for two easy chairs that are fairly small (apartment-sized) for which I would pick an interesting color, blue, terracotta, yellow etc. I would also suggest a larger and more colorful rug, and some colorful art to give this room some drama. Right now it practically disappears, especially when you don't see the pillows. Build a gallery wall around the TV of paintings, drawings, watercolors, whatever speaks to you. For the console buy the window find a colorful ceramic plate instead of the no-color one you have now. I'd also give some thought to buying different drapes, since these don't relate to anything in the room. Cream would be fine, or perhaps cream with a color that is the same as your new chairs.

Nice, cozy space you have. Price will probably determine if you reupholster/slipcover sofa or buy a new one (usually cheaper). Replace the leather chairs with smaller club chairs; current ones seem too big for the space. Upgrade your lighting with table lamps. You could swap out the metal floor lamp with a brass reading lamp, like this (also note size of chairs): Replace rug with something more colorful such as a Persian or kilim, which can be a guide for your sofa upgrade.

If you change out the bulb in the floor lamp to a whiter color, it may help a bit with the lighting in the room. An LED in the 3500-4000K range should do the trick. I think the table lamp is a good size but needs to be on a table that's about 6" higher in order to feel proportionate. A rug pad will certainly help the rug stay in place. If it's a standard size rug, check rugsusa.com. Their prices are good and shipping is free. A pillow or two that ties in all the colors as suggested would help as well. Maybe something like this. https://www.etsy.com/listing/211278615/pillow-cover-crimson-red-gold-navy-blue?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=&ref=sr_gallery-1-40

Let's see - should I buy a new sofa or repair my roof? should I buy a new sofa or fix my basement moisture issues? should I buy a new sofa or pay my taxes? should I buy a new sofa or get surgery that my doctor recommends? Your question is what sofa should I buy to put into a basement that regularly gets 1 to 2 inches of water. You should not buy a a sofa, you should call a contractor and find out what is causing you to get 1 to 2 inches of water in your basement and what it is going to cost to fix the problem. If you have money left over after fixing your water issues then you can buy a sofa without trying to buy something that won't get wet and won't mold when it does get wet. If you have no intention of addressing the water issue and don't mind if the structure of your home is compromised or your health is compromised then buy a sofa that is designed for outdoor use and is designed to get wet. Nothing designed for interior use will be water-friendly.