من الأفضل أن تقارن الباقات.

من الأفضل is a very common expression meaning it is better or it would be better.

A few useful points:

• أفضل is the elative form, which can mean better or best depending on context.
• In this sentence, من الأفضل أن... means it is better to...
• The من here is part of a fixed idiomatic expression. It does not mean a literal English from in this sentence.

So it is best to learn من الأفضل أن... as a chunk:

• من الأفضل أن تنتظر = It is better to wait.
• من الأفضل أن تسأل = It is better to ask.

You may also see الأفضل أن..., which is very close in meaning.

أن is used before an imperfect verb to introduce something like to compare or that you compare.

In Arabic, after expressions such as it is better, I want, it is possible, and so on, you often get:

أن + imperfect verb

So here:

• أن تقارن = to compare / that you compare

Also, أن puts the following imperfect verb into the subjunctive mood.

So grammatically, this is not just any تقارن; it is the subjunctive form after أن.

تقارن comes from the verb قارنَ, which means to compare.

Here it is:

• 2nd person
• masculine singular
• imperfect
• in the subjunctive because of أن

So the full sense is:

• أن تقارن = that you compare / to compare

In unvowelled Arabic writing, you see تقارن, but with full vowels it would be:

• تُقارِنَ

Because Arabic usually does not need to state the subject pronoun when the verb already shows it.

In English, you need you compare.

In Arabic, the verb itself already tells you the subject:

• تقارن = you compare (masculine singular)

So the pronoun أنت is normally omitted unless you want emphasis:

• من الأفضل أن تقارن الباقات = It is better to compare the packages.
• من الأفضل أن أنت تقارن... would be unnatural here.

الباقات is the noun being compared.

Grammatically:

• باقة = one package / bundle / plan
• باقات = packages / bundles / plans
• الباقات = the packages / bundles / plans

So it is:

• a definite
• sound feminine plural
• functioning here as the object of تقارن

In normal Arabic writing, case endings are not shown, so you just see الباقات. In fully vowelled Arabic, the form here would be الباقاتِ.

Good question. In Arabic, قارن can be used in more than one way.

You can say:

• قارن الباقات = compare the packages
• قارن بين الباقات = compare among the packages / compare the packages with one another

So the sentence without بين is perfectly normal.

Using بين often makes the idea of comparison more explicit, but it is not required here.

Not exactly. It is more like advice or a recommendation.

من الأفضل أن... is softer than stronger expressions such as:

• يجب أن... = you must...
• ينبغي أن... = you should...
• عليك أن... = you have to...

So:

• من الأفضل أن تقارن الباقات sounds like It would be better to compare the packages
• not Compare the packages!

In your sentence, تقارن is addressed to one man or to a generic you.

If you change the person addressed, the verb changes:

• to one man: أن تقارن
• to one woman: أن تقارني
• to a group: أن تقارنوا

So you could say:

• من الأفضل أن تقارني الباقات = It is better for you (feminine singular) to compare the packages.
• من الأفضل أن تقارنوا الباقات = It is better for you all to compare the packages.

A helpful pronunciation guide is:

min al-afḍal ʾan tuqārina al-bāqāt

A few pronunciation notes:

• ق in تقارن and باقات is a deep q sound, not an English k
• ض in أفضل is an emphatic Arabic consonant
• ال in الباقات is fully pronounced because ب is a moon letter, not a sun letter

So you say the l clearly in al-bāqāt.

Because أفضل here is not describing الباقات directly.

In this sentence, من الأفضل أن... is an impersonal expression, like English it is better to...

So أفضل is part of that set phrase, and it does not agree with الباقات.

Compare:

• من الأفضل أن تقارن الباقات = It is better to compare the packages.
  Here, أفضل is part of the expression it is better.

But if you were directly describing the packages, that would be a different structure altogether.