I have no experience with the Seagull but if you want a TLR and you want some flexibility, I can wholeheartedly recommend a Mamiya C330. They are pretty close to the proverbial hockey puck in durability and the interchangeable lenses are overall excellent. The only fault I can find with it is that it is big and somewhat unwieldy for handheld use.
I bought my first 330 over 30 years ago. I sold it and regretted it and bought another from a wedding photographer who had used it heavily for many years. It's pretty beat-up with a lot of scratches and spots of missing glaze on the mirror but it still takes great pictures. The built-in bellows makes close-ups as easy as is it gets with a TLR. To get full benefit of close-ups, you will need either a Paramender or a tripod with a center post.
KEH usually has a pretty good selection of Mamiya TLR's and lenses. I've bought a couple of lenses for mine from them and I recommend them. Prices are cheap right now for all medium format equipment. I recently bought a Pentax 645 outfit that is in great condition and I notice the prices have gone down for the camera body in the last month. It's a true "buyer's market" right now so you should be able to locate some nice used gear at bargain prices.