Stored with battery. Empty gas tank. Tires not cracked, but probably no longer soft - ie, gripping issues.
Rust in the tank. Carb(s) will need cleaning/rebuilding if any fuel was in them. Replace the fuel filter. Tires are junk (all motorcycle tires should be changed after 5 years, especially if not used). Possibly ALL rubber is junk: check carb boots for sure. Battery is junk. If it leaked there will be severe rust underneath it Check for nests/animals in the airbox (not a joke) and exhaust. The muffler(s) may be rusted out. Inspect the air filter. Before trying to start the motor, I would first remove the sparkplugs and squirt a small amount of WD40 (or similar) into each cylinder. Then I would try to turn over the motor gently (turn rear wheel with transmission in gear) before replacing the plugs. This will show that the engine is not seized by rust, or will break it free with the least possible damage--hopefully none. Brakes may be seized. Brake fluid attracts moisture, and must be replaced. Both brake systems are very likely to require complete rebuilds if they are hydraulic. It would probably be wise to replace all cables (throttle, clutch, brake and clutch, if any) Everything may need cleaning and lube: chain, swingarm wheel bearings, controls, footpeg pivots, any cables you don't replace. Change oil filter immediately, and after first 1,000km. Before riding, check ALL controls, lights and horn. Make sure that centre/sidestands retract and stay out of the way.
Empty gas tank. Look for rust inside the tank. Seals and gaskets may be dried out and leak. The carburetors may need to be rebuilt. Battery is garbage. Recycle and get a new one. Check the battery connections for corrosion. I would replace the tires. Change the oil before you attempt to start. Remove the spark plugs. Add about 1 teaspoon of oil down each cylinder. Spin the motor over a few times before you start. Check the cables. Throttle. Brake and clutch cable if it has them. If it has a hydraulic clutch drain the fluid and bleed the lines. Check the lines for rot. Check the operation of the brakes before you ride. Oil the chain.
If you have your heart set on a Harley, then get a Harley. Don't settle for something you're not excited about or really want just because someone on YA said to get something else. Harleys are great bikes. Take a Motorcycle Safety Foundation rider ed class if you've never ridden before. They provide the bikes and give you a good start into motorcycling. As far as which Harley to get, if you want a Sportster get one. Personally I'd prefer a Dyna model, but that's just me. I currently ride a 2002 Super Glide. It doesn't leak anything and has never left me on the side of the road. Totally dependable and a blast to ride. Now go sign up for that class and then get that Harley.
