I don't know much about either of the two you are looking at, if I had to buy one or the other I would buy the Diawa Black Gold. But.....
I would save longer to get the best I could afford to buy. Shimano Stadic is a great product, and will provide you with a great service for a long time. As far as price point I would not go below the Stradic.
I don't mean to sound as if "the Budget" is not a good idea, but I would buy a great reel that was used before buying either of the two you mentioned NEW. But if the two you mentioned are the only option, go with the Diawa.
But, again, I would do without and continue to save, and buy the Stradic or better. It's $50.00 more, but a lifetime of difference.
Another option would be the okuma saleena i think it's called. I know most people hear okuma and think oh it's crap. Man let me tell you that new dual over drag system is pretty smooth. They are light weight and seem to work well. I've read user reviews on them and people seem to love them. This is just another option for your 100 dollar price range. I believe wally world has them for 99.00 with rod. Lost key had the penn 750ssm rod and reel for 100, if there is any left. I have the 750ssm and have had it for 2 years now without any problems and it's pulled in 5' sharks weekly.
The Diawa black gold has problems with the line roller freezing up, I know first hand both my son and I bought before Diawa before Shimano big mistake. Won't turn back now. The shimano spheros is 10 times the reel for not much more money if any.
Of the 2 reels I would get the Daiwa BG. They have been on the market a long time. I would save a little more money and get the shimano stradic. I own 3 of the smaller onesand haven't had any problems. Penn reels besides the 706z are a different story.
For my light tackle spinning reels I have a few pfleugers and quantums, and I have been very happy with them. For my heavier tackle, I have fin-nor offshore spinners and they are awesome (above your price limit, but you may be able to find some used on ebay).
Justlast weekI bought one of Penn's new Sargus sg6000 for my wife, and I am impressed with it so far. It is a pretty stout reel; all metal construction, aluminum frame, cover, handle and rotor. Very solid reel for $65 at Lost Key (a great bargain IMO). It lists just about everywhere online for $85.
Some people are very anti-Penn, so watch out for the nay-sayers. Check it out for yourself. Like I said, it is brand new on the market, and Penn seems to be wanting to get people to think of them once again for solid equipment. The new TRQ models are another example of this new Penn attitude. I love those!
Penn has recently introduced a 750 Slammer which will meet your line requirements. The 560 Slammer will come close. The Slammer series is probably the best reel introduced by Penn in a long time. It's a lot better than the Daiwa BG's. but the BG's are bulletproof and I've owned and used a BG60 since the Mid 1980's. You might also look at the Shimano Spheros The 8000 holds
160 of 20 while the 12000 holds 265 of 20. This is mono capacity. If you go to Braid, the reel size can be decreased drastically.
just as garbo mentioned... look into a used reel. if the money is keeping you from getting the reel you want, save a little longer, or buy used. when you look at how many casts youre going to make in the end, its really only going to be a penny or two per throw... so try to hold out a bit longer for what is truly quality.
all that being siad, i have fished a pflueger president (the model below the medalist if im not mistaken) and it was a fantastic reel. i would compare it to an equally sized shimano when i fished it. however, it was a reel that i used while on a friend's boat and now he is having toruble with parts of the reel showing signs of stress from the saltwater environment.
and in addition to that, pflueger ALWAYS takes care of their customers. same guy that i borrowed the reel from, he was cleaning it one day and olst a spring. he called the company to get the part, they didnt charge him for the part, or shipping. they just asked for his address and said thanks for being a loyal customer. i think he is about to send the reel in to have the handle replaced (thats where the unsightly problems are)
having read that, i realize i contradicted myself a bit... but hopefully my opinion and experiences will help your decision! good luck