By long term, do you mean retirement? If so, definitely through a Roth IRA. That way all dividends and profits are tax free.
With ups(Computershare), you have to hold a year, and takes time to sell, where a brokerage house, you can get your money quicker, with no difference in tax liability(dividends and profits), but lose the 5% discount.
When UPS offered stock to hourly's I started buying $25 a week, it added up pretty well. I had more that was in our "Thrift" plan from back in the 80's, that got rolled into an IRA. For the 30 years I put in, I always had faith in the company being a good financial investment. Even though financial advisers tell you not to put all of you eggs in the company basket. I put what I could in that basket and it treated me well. My last 6 years I shifted in the yard for Feeders. My old Preload manager told me I I ever wanted a couple hours OT to come in and sort when I got off my Feeder duty. I just happened to get off just as a couple Amazon trailers hit the doors. I did that for a while, but when that wave of Amazon stuff hit it was like a 4-5 foot high wave coming down the belts. Now that Amazon is doing a lot of there own shipping, and dividing it up with other shippers, I wonder what that will do to our financial security. I would still say invest in UPS. You really should have a financial adviser, if you already don't. Mine made me enough that even if the pension went belly up, I'm pretty secure. Sock what you can in your 401, good luck, if you can stick it out, it will pay off.
Fractional pieces for the long term is confusing to me. If you buy through your paycheck it will be fractional as they deduct a set amount each week and then every quarter they will use that money to buy you however many shares they can with it and they do divide it into fractions. I've been buying $60 a week since we went public with an extra $10k purchase when the stock got silly low in 2008 (right around $40 a share if I recall) and one other $5K purchase at some other point when it was fairly low and I currently have more than 200k worth of stock. It used to be a 10 percent discount but even the 5 percent discount adds up over time. If you are in it for the long game it can pay off. I consider this my emergency fund as it is possible I could access it if the need ever arose. I actually have a real emergency fund which I think is completely necessary if you are going to invest otherwise I think it's too easy to convince yourself you need that money regardless of tax hits etc. I max both our Roth's every year and also have been hitting our 401k's pretty heavy maxing them the last couple of years. This money can't really be pulled so these are my retirement accounts with some small hope that I will receive a pension. I also dump money extra month into the mortgage with the thought that this is another form of a retirement account as clearly nobody should be making mortgage payments in retirement.
Also, UPS is a dividend stock so you will need to pay taxes even if you roll than money into more shares which I strongly recommend. Made the mistake when I was younger and received a tax bill form the IRS after a few years. I think I just ignored the tax document they sent me thinking that if I wasn't taking cash I didn't have to pay.
I think back when I was buying it through DESP, it was a 10% discount in price and that seems to have changed to a 5% discount.
What I remember as one of the biggest advantages of the program was that you got the shares at a discount from the price at the beginning of the quarter or the end of the quarter, whichever was the lower price.
That worked out great sometimes when the stock rose for the three months they took the money out of your check!