Saw this post and was all ready trot out my personal list of lens favorites, but then looking over the many excellent suggestions above, there's little I would add to this. It is interesting though that you say you want to do landscapes (will call that outdoors too), street, and...stuff. I'd point out here that the needs of a photographer shooting landscapes versus street are quite different IMHO. Toss in portraiture, macro, action, and other types, and again, these all have other needs as well. Early on (12 years ago) when I got back in to photography, I assumed that if I had a range of lenses spanning a wide range of lengths (I was thinking then of something like about 18mm to about 300mm) that this would, should cover my needs for photography. 60 or 70 (likely more than that) lenses later, I come realize that every lens has a specific purpose but it also has some versatility.
For me, doing landscapes (and this is what I tend to concentrate on), I prefer UWA (ultra wide lenses) like the DA 15 limited, actually my favorite lens on a cropped sensor is the DA 12-24 f4 lens, but as many have written about here, the DA 15 Limited is an amazing lens all by itself. At the same time for landscapes I have and do use the DA*16-50, DA*50-135, and although I'm now using the K-1 full frame system DFA 70-200, I used the Tamron 70-200 at times as well, because sometimes I want to shoot a landscape from say on a fence outside the property and having a longer reach can really help. Occasionally, I've also used the DA 100 Macro for landscapes. It's sooo sharp in places like Yosemite NP, the macro lens really brings out the detail. Oddly one of the few DA lenses that I don't have is the DA 18-135, why? well because it was released well after I'd acquired a bunch of other lenses and I really don't have the need for it and early on, I came to prefer lenses with a constant aperture versus a lens like the DA 18-135 which is a variable aperture lens. Regardless, when I was starting out, I purchased a Sigma 18-125mm lens, which gave me a great range of lengths and I was able to learn with it as well as produce some landscape images that I still regard as right up there in my best work group. So...what I'm backing my way into is that I'd agree with the suggestions of the DA 18-135 for you for outdoors and landscapes. Spend more money on a good tripod too, as this is the other half of a good landscape system.
For street, other factors should be considered. Typically, you should want a fast lens f2.8 or better, it would also help if the lens itself was small so that the camera + lens is not so imposing on your potential subjects, and also, such that you can sorta hide or de-emphasise the camera which 'should' allow for more natural responses from street subjects. For this, IMHO, neither the DA 15 nor the DA 18-135 would be the best choices as the DA 15 is too wide for this purpose and UWA lenses can make peoples figures, look a bit unnatural, the DA 18-135 being a zoom lens might require more fiddle time to get the right framing of the subjects. If I recall correctly classic street stuff should be done with something between 35mm and 50mm and either the DA 35 or DA 50 1.8 might be ideal for this usage.
Ok, given that all of the above is just my opinion and that one should be able to produce good results with most camera / lens combinations, the above may all be moot, but I wanted to expand the discussion with a bit more what and why here. Given that you have the DA 15 and that many of the posters above recommend the DA 18-135 as your next lens, I'd go with that too.
---------- Post added 02-18-20 at 09:12 AM ----------
Originally posted by Bucketlist21 Thank you all ! I am very impressed with how helpful everyone is. Makes this whole thing even more enjoyable.
Oh, we're all very helpful at spending others funds on gear...